/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.web.context.request.async;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.web.context.request.NativeWebRequest;

import java.util.List;

/**
 * Assists with the invocation of {@link DeferredResultProcessingInterceptor}'s.
 *
 * @author Rossen Stoyanchev
 * @since 3.2
 */
class DeferredResultInterceptorChain {

    private static final Log logger = LogFactory.getLog(DeferredResultInterceptorChain.class);

    private final List<DeferredResultProcessingInterceptor> interceptors;

    private int preProcessingIndex = -1;


    public DeferredResultInterceptorChain(List<DeferredResultProcessingInterceptor> interceptors) {
        this.interceptors = interceptors;
    }

    public void applyBeforeConcurrentHandling(NativeWebRequest request, DeferredResult<?> deferredResult)
            throws Exception {

        for (DeferredResultProcessingInterceptor interceptor : this.interceptors) {
            interceptor.beforeConcurrentHandling(request, deferredResult);
        }
    }

    public void applyPreProcess(NativeWebRequest request, DeferredResult<?> deferredResult) throws Exception {
        for (DeferredResultProcessingInterceptor interceptor : this.interceptors) {
            interceptor.preProcess(request, deferredResult);
            this.preProcessingIndex++;
        }
    }

    public Object applyPostProcess(NativeWebRequest request, DeferredResult<?> deferredResult,
                                   Object concurrentResult) {

        try {
            for (int i = this.preProcessingIndex; i >= 0; i--) {
                this.interceptors.get(i).postProcess(request, deferredResult, concurrentResult);
            }
        }
        catch (Throwable ex) {
            return ex;
        }
        return concurrentResult;
    }

    public void triggerAfterTimeout(NativeWebRequest request, DeferredResult<?> deferredResult) throws Exception {
        for (DeferredResultProcessingInterceptor interceptor : this.interceptors) {
            if (deferredResult.isSetOrExpired()) {
                return;
            }
            if (!interceptor.handleTimeout(request, deferredResult)) {
                break;
            }
        }
    }

    /**
     * Determine if further error handling should be bypassed.
     *
     * @return {@code true} to continue error handling, or false to bypass any further
     * error handling
     */
    public boolean triggerAfterError(NativeWebRequest request, DeferredResult<?> deferredResult, Throwable ex)
            throws Exception {

        for (DeferredResultProcessingInterceptor interceptor : this.interceptors) {
            if (deferredResult.isSetOrExpired()) {
                return false;
            }
            if (!interceptor.handleError(request, deferredResult, ex)) {
                return false;
            }
        }
        return true;
    }

    public void triggerAfterCompletion(NativeWebRequest request, DeferredResult<?> deferredResult) {
        for (int i = this.preProcessingIndex; i >= 0; i--) {
            try {
                this.interceptors.get(i).afterCompletion(request, deferredResult);
            }
            catch (Throwable ex) {
                logger.trace("Ignoring failure in afterCompletion method", ex);
            }
        }
    }

}
